|Full Name||Saiki Kuniharu|
|Age||39 years old|
|Affiliation||Weekly Shounen Cognac|
|Manga Debut||Chapter 01|
|Anime Debut||Season 1 Episode 1|
|English Voice||Chuck Huber|
|Japanese Voice||Mitsuo Iwata|
|Live Action||Tanabe Seiichi|
Kuniharu Saiki(斉木 國春, さいき くにはる lit. Saiki Kuniharu) is the father of Kusuo and Kusuke and the husband of Kurumi. Kuniharu is one of the supporting characters of the series and was starred by Tanabe Seiichi in the live action of the series.
Kuniharu often wears a suit and tie when going to work. He sports a pair of glasses and has brown hair and eyes, a change from his first appearance in the one-shot volume of the series where he has black hair and eyes.
He is sloppy and slovenly, often begging with disgusting teary faces towards his son. He is a layman who is often seen licking the shoes of his boss. He works as a manga editor. His special skill is flattering his boss. His father (paternal grandfather of Kusuo and Kusuke) has passed away while his mother (paternal grandmother of Kusuo and Kusuke) lives in a family house.
- After meeting his wife Saiki Kurumi on November 22, they got married a year later on the same day.
- He unknowingly met Riki's father in the past and he is part of the reason how he met his wife.
- He mentions that his mother is still alive while his father is deceased.
- During one of his lover's quarrel with Kurumi, it resulted in Kusuo finding out that both have the same level of love for each other with a result of 38,689 in Kusuo's affection meter.
|v · e||Saiki Family|
|Members:||Saiki Kumi · Saiki Kumagorou · Saiki Kurumi · Saiki Kuniharu · Saiki Kusuke · Saiki Kusuo|
|Miscellaneous:||Anpu · Pushi · Warp|